Mine

#!/usr/bin/perl -w


# Load modules
use Switch;
use IO::Seekable;
use IO::Handle;

# Init vars
%logs = ('mx','/sonic-logs/mail/maillog.mx',
'mail','/sonic-logs/mail/maillog.mail',
'rad','/sonic-logs/radmon/today',
'dhcp','/sonic-logs/dhcpd/dhcpd.log',
'pop','/sonic-logs/mail/popper',
'pwd','/sonic-info/passwd-withgcos');
$match = 0;
$lines = 0;
$help = " Usage: dst [OPTIONS] [LOG] STRING
 Description: Looks through [LOG] for lines that contain STRING
 
 Behavior:
   -t            Given log is tailed
   -f            Follows the end of the file
   -w            Searches for exact word matches
   -i            Case insensitive search
   -v            Display verbose options on script initiation
   -n [LINES]    Implies tail, set number to lines to [LINES]
  
 LOG may include any of the following...
   mail(default) Parse $logs{'mail'}
   mx            Parse $logs{'mx'}
   pop           Parse $logs{'pop'}
   rad           Parse $logs{'rad'}
   pwd           Parse $logs{'pwd'}
   dhcp          Parse $logs{'dhcp'}
  
 Miscellaneous:
  --help      Displays this help  \n\n\n";
# By default we will match anything
$string = 'ANY';
# By default we don't tail the log
$tail = 0;
# By default we don't follow a growing log
$follow = 0;
# By default search is case sensitive
$case = 1;
# Default string (will be replaced by $string)
$pattern = 'STRING';
# Do not show verbose output by default
$verbose = 0;
# Number of lines we're shooting to tail
$tlines = 10000;
# Our default log file
$log = 'mail';
# Set our line length for default log
$seek = -250;
# As we go through arguments lets pay attention to which one we're looking at
$key = 0;
# Parse arguments
if ($#ARGV > -1) {
	foreach (@ARGV) {
		switch ($_) {
			case '--help' { die($help) }
			# Parse flags
			case m/^-/ {
				if($_ =~ m/f/) { $follow = 1; }
				if($_ =~ m/n/) { 
					if($ARGV[($key+1)] =~ m/[0-9]+/) { 
						$tlines = $ARGV[($key+1)];
						$tail = 1;
					}
				}
				if($_ =~ m/v/) { $verbose = 1; }
				if($_ =~ m/t/) { $tail = 1; }
				if($_ =~ m/i/) { $case = 0; }
				if($_ =~ m/v/) { $verbose = 1; }
				if($_ =~ m/w/) { $pattern = '[^a-zA-Z0-9_]STRING[^a-zA-Z0-9_]'; }
			}
			case /^mail$|^mx$|^rad$|^dhcp$|^pop$|^pwd$/ { 
				# Pick a log to parse
				$log = $_;
				# Set byte value for a line in each log so we can seek back for our tail
				switch($_) {
					case 'mail' { $seek = -250; }
					case 'mx' { $seek = -250; }
					case 'rad' { $seek = -100; }
					case 'dhcp' { $seek = -200; }
					case 'pop' { $seek = -100; }
					case 'pwd' { $seek = -100; }
				}
			}
			# If the last argument isn't an option we'll search for it
			else { if($_ eq $ARGV[-1] & $_ ne $tlines) { $string = $_; } }
		}
	$key++;
	}
}

$pattern =~ s/STRING/$string/;

if($string ne 'ANY') { print 'Checking for instances of "'.$string.'" in file "'.$logs{$log}.'"'; }
if($verbose | $string ne 'ANY') { print "\nMatch Case: ".($case ? 'TRUE' : 'FALSE')."\nTailing log: ".($tail ? 'TRUE' : 'FALSE')."\nFollows log: ".($follow ? 'TRUE' : 'FALSE')."\nExact Match: ".($pattern eq $string ? 'FALSE' : 'TRUE'); } 
print "\n\n";
# Open log for parsing
open(LOGF, $logs{$log}) || die 'Didn\'t work.';

# If we're tailing, go to tail position
if($tail) { seek(LOGF,$seek*$tlines,SEEK_END) }
FOLLOW:
while (<LOGF>) {
	if($tail) { $lines++; }
	if($string ne 'ANY') { 
		if($case == 0) { 
			if($_ =~ m/$pattern/i) { 
				$match++;
				print $_; 
			} 
		}
		else { 
			if($_ =~ m/$pattern/) {
				$match++;
				print $_; 
			} 
		}
	}
	else { print $_; }
}

# If we're following the file let's wait a couple seconds then clear EOF before continuing
if($follow) { 
	sleep(5);
	LOGF->clearerr();
	goto FOLLOW; 
}

close(LOGF);
if($string ne 'ANY') { print "\n\n".'Found '.$match.' instances of "'.$string.'" in file "'.$logs{$log}.'"'; }
if($verbose | $string ne 'ANY') { print	"\n\nMatch Case: ".($case ? 'TRUE' : 'FALSE')."\nTailing log: ".($tail ? $lines.' lines' : 'FALSE')."\nExact Match: ".($pattern eq $string ? 'FALSE' : 'TRUE')."\n\n"; }
print "\n";